1. Field of the Invention
The present invention relates to a starting apparatus for engines and, more particularly, to a starting apparatus for use in a 4-cycle gasoline engine of the type which is to be started by a starter motor.
2. Description of the Prior Art
A conventional starting apparatus for a 4-cycle gasoline engine of this type is schematically shown in FIG. 19. A flywheel 4 having a cooling fan 3 formed integrally therewith is mounted to a crankshaft 2 projecting from an engine body 1. A ring gear 5 is mounted on the outer periphery of flywheel 4. Mounted to one side of the engine body 1 is a starter motor 6 having a length substantially equal to the width of the engine body 1 and from which extends a driving shaft 7 to which a driving gear 8 is axially movably fixed. As the starter motor 6 is driven, the driving gear 8 projects forward to bring the driving gear 8 into engagement with the ring gear 5 so that the crankshaft 2 is driven to rotate through the flywheel 4. When the engine is started, the driving gear 8 retracts to its original position to disengage the driving gear 8 from the ring gear 5. A power source for driving the starter motor 6 is separately provided in the form of a battery of about one half the size of the engine body 1, which is connected to the starter motor 6.
As above noted, the conventional 4-cycle gasoline engine requires a starter motor 6 having a body portion of a length substantially equal to the width of the engine body 1. Therefore, such engine has a disadvantage in that if the starter motor 6 is mounted to the engine body 1, the external size of the engine as a whole is exceptionally large. Another disadvantage is that driving such a large-size starter motor 6 requires a large-size battery as a power source which, as above noted, must be mounted in position separately from the engine body 1 since it is impractical to mount the battery to the engine body 1. Further, with conventional engines of the type designed to be mounted to a field work machine, including engines of recoil starter specification and those of starter motor specification, one disadvantage is that, if the engine is of the starter motor specification, an extra space is required for mounting the battery, which permits no easy mounting of the engine on the field work machine, if the machine is of the recoil starter specification; and in such case, it is further required that wiring arrangement be made between the battery and the starter motor. A further disadvantage is that if an engine of starter motor specification is to be mounted in addition to an engine of recoil starter specification which is provided with no ring gear 5, the flywheel 4 portion of the latter engine must be totally replaced.
It is noted that 2-cycle engines of a very small capacity of less than 50 cc have been known which are equipped with a starter motor and a battery, both of small size. However, no engine of such arrangement has been known as far as 4-cycle engines of small capacities ranging from about 50 cc to about 250 cc are concerned, and it has been considered to be impractical to obtain an engine of such arrangement.
The present invention is directed to eliminating the above noted disadvantages with the prior art 4-cycle gasoline engines and accordingly it is a primary object of the invention to provide a starting apparatus which is compact in construction and permits a starter motor and a battery together to be integrally incorporated into an engine body.